Among those aged 15 to 24, the figure rises to 20 percent.
The mobile phone has also become a magnet of infidelity testing.
Forty-five percent of women owned up to secretly checking the text messages on their partner's phone, compared to 31 percent of men.
Philippa O'Sullivan, 15, from near Basingstoke, in southern England, said using text messages to finish relationships was common among teen-agers, many of whom "find it easier to talk by text."
"I've heard of lots of people, including a couple of my friends, being dumped that way," O'Sullivan said.
The poll, by market research firm NOP for Sicap, a messaging services provider based in Bern, Switzerland, also found that 44 percent had used text messages to flirt; among the 14 to 24-year-olds, the figure rose to 75 percent.
Some 31 percent of adults said they had sent a love letter by text — even among the over-65s, nine percent had done so — and 30 percent said they had argued via SMS, or Short Message Service.
Two percent say they have used text messages to quit a job.
In March alone, according to Britain's Mobile Data Association, Britons sent 2.1 billion text messages, a 25 percent increase from the same month last year.
NOP questioned 771 people aged 15 and over from April 23 to 25 for the poll. No margin of error was given, but on a sample of this size it is likely to be around 3 percentage points either way.